During the roll-to-roll processing in roller assemblies, when substrates or films are transported from one roller to another roller, the substrates or films may have patterns that were formed on the substrates. In order to prevent the patterns from being damaged, the substrates or films are transported through a step roller so that the patterns do not contact the rollers directly. Since the patterns do not contact the rollers through the step roller, the substrates or films are transported without damaging the patterns on them.
However, conventional step rollers do not support the middle of the substrate or film they are transporting because the patterns are in the middle of the substrate. During transporting the substrate through the step roller, stress is generated towards the substrate from the bending moment. Because the substrate is not supported in the middle, the stress generated from the bending moment may cause the substrate or film to be wrinkled or damaged. If the substrate is damaged, the substrate is not able to be properly transported. In addition, the pattern on the substrate may also be damaged.